ABSTRACT Bladder cancer (BCa) is one of the most common cancers in veterans. There is no significant improvement in overall survival for advanced BCa over the last three decades. Immunotherapy with immune checkpoint inhibitors showed promising anti-tumor activity in this disease. However, less than 20% of patients respond to this treatment. Various strategies, including combination with other therapies, are being explored to enhance the efficacy of immunotherapy. With the funding of the VA Career Development Award-2 and VA Merit, we developed a BCa-specific PLZ4-nanoporphyrin (PNP) that combines imaging-guided chemotherapy, photodynamic and photothermal therapies into a single platform. All three therapies have been shown to potentiate immunotherapy with cancer vaccines. Here we propose to determine whether the efficacy of immunotherapy with an immune checkpoint inhibitor can be enhanced via combining immunotherapy with chemotherapy, photodynamic and photothermal therapies using PNP. Because PNP can target the mouse BCa cell line MB49, we will first conduct the efficacy studies in immunocompetent mice carrying MB49 syngeneic tumors. Recently, we developed humanized mice in which the immune cells of the host mice are derived from humans. We will implant into these mice patient-derived xenografts (PDX) that are developed from unselected and uncultured human patient cancer tissues in order to validate the MB49 cell line studies in mice. We will then translate the studies into BCa transgenic mice to determine whether PNP can potentiate immunotherapy. Mechanisms of resistance will also be studied. Since we have already held a pre-IND (Investigational New Drug) consultation with the US Food and Drug Administration for PNP, successful completion of this project can lead to a clinical trial to combine PNP with immunotherapy in BCa.